<?php
namespace Lib;

class XssClean
{
    /**
     * Random Hash for protecting URLs
     *
     * @var string
     * @access protected
     */
    protected $_xss_hash            = '';
    /**
     * Random Hash for Cross Site Request Forgery Protection Cookie
     *
     * @var string
     * @access protected
     */
    protected $_csrf_hash           = '';
    /**
     * Expiration time for Cross Site Request Forgery Protection Cookie
     * Defaults to two hours (in seconds)
     *
     * @var int
     * @access protected
     */
    protected $_csrf_expire         = 7200;
    /**
     * Token name for Cross Site Request Forgery Protection Cookie
     *
     * @var string
     * @access protected
     */
    protected $_csrf_token_name     = 'ci_csrf_token';
    /**
     * Cookie name for Cross Site Request Forgery Protection Cookie
     *
     * @var string
     * @access protected
     */
    protected $_csrf_cookie_name    = 'ci_csrf_token';
    /**
     * List of never allowed strings
     *
     * @var array
     * @access protected
     */
    protected $_never_allowed_str = array(
        'document.cookie'   => '[removed]',
        'document.write'    => '[removed]',
        '.parentNode'       => '[removed]',
        '.innerHTML'        => '[removed]',
        'window.location'   => '[removed]',
        '-moz-binding'      => '[removed]',
        '<!--'              => '&lt;!--',
        '-->'               => '--&gt;',
        '<![CDATA['         => '&lt;![CDATA[',
        '<comment>'         => '&lt;comment&gt;'
    );

    /* never allowed, regex replacement */
    /**
     * List of never allowed regex replacement
     *
     * @var array
     * @access protected
     */
    protected $_never_allowed_regex = array(
        'javascript\s*:',
        'expression\s*(\(|&\#40;)', // CSS and IE
        'vbscript\s*:', // IE, surprise!
        'Redirect\s+302',
        "([\"'])?data\s*:[^\\1]*?base64[^\\1]*?,[^\\1]*?\\1?"
    );

    /**
     * Constructor
     *
     * @return  void
     */
    public function __construct()
    {

    }

    // --------------------------------------------------------------------

    /**
     * Verify Cross Site Request Forgery Protection
     *
     * @return  object
     */
    public function csrf_verify()
    {
        // If it's not a POST request we will set the CSRF cookie
        if (strtoupper($_SERVER['REQUEST_METHOD']) !== 'POST')
        {
            return $this->csrf_set_cookie();
        }

        // Do the tokens exist in both the _POST and _COOKIE arrays?
        if ( ! isset($_POST[$this->_csrf_token_name], $_COOKIE[$this->_csrf_cookie_name]))
        {
            $this->csrf_show_error();
        }

        // Do the tokens match?
        if ($_POST[$this->_csrf_token_name] != $_COOKIE[$this->_csrf_cookie_name])
        {
            $this->csrf_show_error();
        }

        // We kill this since we're done and we don't want to
        // polute the _POST array
        unset($_POST[$this->_csrf_token_name]);

        // Nothing should last forever
        unset($_COOKIE[$this->_csrf_cookie_name]);
        $this->_csrf_set_hash();
        $this->csrf_set_cookie();

        return $this;
    }

    // --------------------------------------------------------------------

    /**
     * Set Cross Site Request Forgery Protection Cookie
     *
     * @return  object
     */
    public function csrf_set_cookie()
    {
        $expire = time() + $this->_csrf_expire;
        $secure_cookie = 1;

        if ($secure_cookie && (empty($_SERVER['HTTPS']) OR strtolower($_SERVER['HTTPS']) === 'off'))
        {
            return FALSE;
        }

        setcookie($this->_csrf_cookie_name, $this->_csrf_hash, $expire, '/', 'am.xiaojukeji.com', $secure_cookie);

        return $this;
    }

    // --------------------------------------------------------------------

    /**
     * Show CSRF Error
     *
     * @return  void
     */
    public function csrf_show_error()
    {
        show_error('The action you have requested is not allowed.');
    }

    // --------------------------------------------------------------------

    /**
     * Get CSRF Hash
     *
     * Getter Method
     *
     * @return  string  self::_csrf_hash
     */
    public function get_csrf_hash()
    {
        return $this->_csrf_hash;
    }

    // --------------------------------------------------------------------

    /**
     * Get CSRF Token Name
     *
     * Getter Method
     *
     * @return  string  self::csrf_token_name
     */
    public function get_csrf_token_name()
    {
        return $this->_csrf_token_name;
    }

    // --------------------------------------------------------------------

    /**
     * XSS Clean
     *
     * Sanitizes data so that Cross Site Scripting Hacks can be
     * prevented.  This function does a fair amount of work but
     * it is extremely thorough, designed to prevent even the
     * most obscure XSS attempts.  Nothing is ever 100% foolproof,
     * of course, but I haven't been able to get anything passed
     * the filter.
     *
     * Note: This function should only be used to deal with data
     * upon submission.  It's not something that should
     * be used for general runtime processing.
     *
     * This function was based in part on some code and ideas I
     * got from Bitflux: http://channel.bitflux.ch/wiki/XSS_Prevention
     *
     * To help develop this script I used this great list of
     * vulnerabilities along with a few other hacks I've
     * harvested from examining vulnerabilities in other programs:
     * http://ha.ckers.org/xss.html
     *
     * @param   mixed   string or array
     * @param   bool
     * @return  string
     */
    public function xss_clean($str, $is_image = FALSE)
    {
        /*
         * Is the string an array?
         *
         */
        if (is_array($str))
        {
            // The each() function is deprecated. This message will be suppressed on further calls
            foreach ($str as $key => $value)
            {
                $str[$key] = $this->xss_clean($str[$key]);
            }
            // while (list($key) = each($str))
            // {
            //     $str[$key] = $this->xss_clean($str[$key]);
            // }

            return $str;
        }

        /*
         * Remove Invisible Characters
         */
        $str = $this->remove_invisible_characters($str);

        // Validate Entities in URLs
        $str = $this->_validate_entities($str);

        /*
         * URL Decode
         *
         * Just in case stuff like this is submitted:
         *
         * <a href="http://%77%77%77%2E%67%6F%6F%67%6C%65%2E%63%6F%6D">Google</a>
         *
         * Note: Use rawurldecode() so it does not remove plus signs
         *
         */
        $str = rawurldecode($str);

        /*
         * Convert character entities to ASCII
         *
         * This permits our tests below to work reliably.
         * We only convert entities that are within tags since
         * these are the ones that will pose security problems.
         *
         */

        $str = preg_replace_callback("/[a-z]+=([\'\"]).*?\\1/si", array($this, '_convert_attribute'), $str);

        $str = preg_replace_callback("/<\w+.*?(?=>|<|$)/si", array($this, '_decode_entity'), $str);

        /*
         * Remove Invisible Characters Again!
         */
        $str = $this->remove_invisible_characters($str);

        /*
         * Convert all tabs to spaces
         *
         * This prevents strings like this: ja  vascript
         * NOTE: we deal with spaces between characters later.
         * NOTE: preg_replace was found to be amazingly slow here on
         * large blocks of data, so we use str_replace.
         */

        if (strpos($str, "\t") !== FALSE)
        {
            $str = str_replace("\t", ' ', $str);
        }

        /*
         * Capture converted string for later comparison
         */
        $converted_string = $str;

        // Remove Strings that are never allowed
        $str = $this->_do_never_allowed($str);

        /*
         * Makes PHP tags safe
         *
         * Note: XML tags are inadvertently replaced too:
         *
         * <?xml
         *
         * But it doesn't seem to pose a problem.
         */
        if ($is_image === TRUE)
        {
            // Images have a tendency to have the PHP short opening and
            // closing tags every so often so we skip those and only
            // do the long opening tags.
            $str = preg_replace('/<\?(php)/i', "&lt;?\\1", $str);
        }
        else
        {
            $str = str_replace(array('<?', '?'.'>'),  array('&lt;?', '?&gt;'), $str);
        }

        /*
         * Compact any exploded words
         *
         * This corrects words like:  j a v a s c r i p t
         * These words are compacted back to their correct state.
         */
        $words = array(
            'javascript', 'expression', 'vbscript', 'script', 'base64',
            'applet', 'alert', 'document', 'write', 'cookie', 'window'
        );

        foreach ($words as $word)
        {
            $temp = '';

            for ($i = 0, $wordlen = strlen($word); $i < $wordlen; $i++)
            {
                $temp .= substr($word, $i, 1)."\s*";
            }

            // We only want to do this when it is followed by a non-word character
            // That way valid stuff like "dealer to" does not become "dealerto"
            $str = preg_replace_callback('#('.substr($temp, 0, -3).')(\W)#is', array($this, '_compact_exploded_words'), $str);
        }

        /*
         * Remove disallowed Javascript in links or img tags
         * We used to do some version comparisons and use of stripos for PHP5,
         * but it is dog slow compared to these simplified non-capturing
         * preg_match(), especially if the pattern exists in the string
         */
        do
        {
            $original = $str;

            if (preg_match("/<a/i", $str))
            {
                $str = preg_replace_callback("#<a\s+([^>]*?)(>|$)#si", array($this, '_js_link_removal'), $str);
            }

            if (preg_match("/<img/i", $str))
            {
                $str = preg_replace_callback("#<img\s+([^>]*?)(\s?/?>|$)#si", array($this, '_js_img_removal'), $str);
            }

            if (preg_match("/script/i", $str) OR preg_match("/xss/i", $str))
            {
                $str = preg_replace("#<(/*)(script|xss)(.*?)\>#si", '[removed]', $str);
            }
        }
        while($original != $str);

        unset($original);

        // Remove evil attributes such as style, onclick and xmlns
        $str = $this->_remove_evil_attributes($str, $is_image);

        /*
         * Sanitize naughty HTML elements
         *
         * If a tag containing any of the words in the list
         * below is found, the tag gets converted to entities.
         *
         * So this: <blink>
         * Becomes: &lt;blink&gt;
         */
        $naughty = 'alert|applet|audio|basefont|base|behavior|bgsound|blink|body|embed|expression|form|frameset|frame|head|html|ilayer|iframe|input|isindex|layer|link|meta|object|plaintext|style|script|textarea|title|video|xml|xss';
        $str = preg_replace_callback('#<(/*\s*)('.$naughty.')([^><]*)([><]*)#is', array($this, '_sanitize_naughty_html'), $str);

        /*
         * Sanitize naughty scripting elements
         *
         * Similar to above, only instead of looking for
         * tags it looks for PHP and JavaScript commands
         * that are disallowed.  Rather than removing the
         * code, it simply converts the parenthesis to entities
         * rendering the code un-executable.
         *
         * For example: eval('some code')
         * Becomes:     eval&#40;'some code'&#41;
         */
        $str = preg_replace('#(alert|cmd|passthru|eval|exec|expression|system|fopen|fsockopen|file|file_get_contents|readfile|unlink)(\s*)\((.*?)\)#si', "\\1\\2&#40;\\3&#41;", $str);


        // Final clean up
        // This adds a bit of extra precaution in case
        // something got through the above filters
        $str = $this->_do_never_allowed($str);

        /*
         * Images are Handled in a Special Way
         * - Essentially, we want to know that after all of the character
         * conversion is done whether any unwanted, likely XSS, code was found.
         * If not, we return TRUE, as the image is clean.
         * However, if the string post-conversion does not matched the
         * string post-removal of XSS, then it fails, as there was unwanted XSS
         * code found and removed/changed during processing.
         */

        if ($is_image === TRUE)
        {
            return ($str == $converted_string) ? TRUE: FALSE;
        }

        return $str;
    }

    // --------------------------------------------------------------------

    /**
     * Random Hash for protecting URLs
     *
     * @return  string
     */
    public function xss_hash()
    {
        if ($this->_xss_hash == '')
        {
            mt_srand();
            $this->_xss_hash = md5(time() + mt_rand(0, 1999999999));
        }

        return $this->_xss_hash;
    }

    // --------------------------------------------------------------------

    /**
     * HTML Entities Decode
     *
     * This function is a replacement for html_entity_decode()
     *
     * The reason we are not using html_entity_decode() by itself is because
     * while it is not technically correct to leave out the semicolon
     * at the end of an entity most browsers will still interpret the entity
     * correctly.  html_entity_decode() does not convert entities without
     * semicolons, so we are left with our own little solution here. Bummer.
     *
     * @param   string
     * @param   string
     * @return  string
     */
    public function entity_decode($str, $charset='UTF-8')
    {
        if (stristr($str, '&') === FALSE)
        {
            return $str;
        }

        $str = html_entity_decode($str, ENT_COMPAT, $charset);
        $str = preg_replace('~&#x(0*[0-9a-f]{2,5})~ei', 'chr(hexdec("\\1"))', $str);
        return preg_replace('~&#([0-9]{2,4})~e', 'chr(\\1)', $str);
    }

    // --------------------------------------------------------------------

    /**
     * Filename Security
     *
     * @param   string
     * @param   bool
     * @return  string
     */
    public function sanitize_filename($str, $relative_path = FALSE)
    {
        $bad = array(
            "../",
            "<!--",
            "-->",
            "<",
            ">",
            "'",
            '"',
            '&',
            '$',
            '#',
            '{',
            '}',
            '[',
            ']',
            '=',
            ';',
            '?',
            "%20",
            "%22",
            "%3c",      // <
            "%253c",    // <
            "%3e",      // >
            "%0e",      // >
            "%28",      // (
            "%29",      // )
            "%2528",    // (
            "%26",      // &
            "%24",      // $
            "%3f",      // ?
            "%3b",      // ;
            "%3d"       // =
        );

        if ( ! $relative_path)
        {
            $bad[] = './';
            $bad[] = '/';
        }

        $str = $this->remove_invisible_characters($str, FALSE);
        return stripslashes(str_replace($bad, '', $str));
    }

    // ----------------------------------------------------------------

    /**
     * Compact Exploded Words
     *
     * Callback function for xss_clean() to remove whitespace from
     * things like j a v a s c r i p t
     *
     * @param   type
     * @return  type
     */
    protected function _compact_exploded_words($matches)
    {
        return preg_replace('/\s+/s', '', $matches[1]).$matches[2];
    }

    // --------------------------------------------------------------------

    /*
     * Remove Evil HTML Attributes (like evenhandlers and style)
     *
     * It removes the evil attribute and either:
     *  - Everything up until a space
     *      For example, everything between the pipes:
     *      <a |style=document.write('hello');alert('world');| class=link>
     *  - Everything inside the quotes
     *      For example, everything between the pipes:
     *      <a |style="document.write('hello'); alert('world');"| class="link">
     *
     * @param string $str The string to check
     * @param boolean $is_image TRUE if this is an image
     * @return string The string with the evil attributes removed
     */
    protected function _remove_evil_attributes($str, $is_image)
    {
        // All javascript event handlers (e.g. onload, onclick, onmouseover), style, and xmlns
        $evil_attributes = array('on\w*', 'style', 'xmlns', 'formaction');

        if ($is_image === TRUE)
        {
            /*
             * Adobe Photoshop puts XML metadata into JFIF images,
             * including namespacing, so we have to allow this for images.
             */
            unset($evil_attributes[array_search('xmlns', $evil_attributes)]);
        }

        do {
            $count = 0;
            $attribs = array();

            // find occurrences of illegal attribute strings with quotes (042 and 047 are octal quotes)
            preg_match_all('/('.implode('|', $evil_attributes).')\s*=\s*(\042|\047)([^\\2]*?)(\\2)/is', $str, $matches, PREG_SET_ORDER);

            foreach ($matches as $attr)
            {
                $attribs[] = preg_quote($attr[0], '/');
            }

            // find occurrences of illegal attribute strings without quotes
            preg_match_all('/('.implode('|', $evil_attributes).')\s*=\s*([^\s>]*)/is', $str, $matches, PREG_SET_ORDER);

            foreach ($matches as $attr)
            {
                $attribs[] = preg_quote($attr[0], '/');
            }

            // replace illegal attribute strings that are inside an html tag
            if (count($attribs) > 0)
            {
                $str = preg_replace('/(<?)(\/?[^><]+?)([^A-Za-z<>\-])(.*?)('.implode('|', $attribs).')(.*?)([\s><]?)([><]*)/i', '$1$2 $4$6$7$8', $str, -1, $count);
            }

        } while ($count);

        return $str;
    }

    // --------------------------------------------------------------------

    /**
     * Sanitize Naughty HTML
     *
     * Callback function for xss_clean() to remove naughty HTML elements
     *
     * @param   array
     * @return  string
     */
    protected function _sanitize_naughty_html($matches)
    {
        // encode opening brace
        $str = '&lt;'.$matches[1].$matches[2].$matches[3];

        // encode captured opening or closing brace to prevent recursive vectors
        $str .= str_replace(array('>', '<'), array('&gt;', '&lt;'),
            $matches[4]);

        return $str;
    }

    // --------------------------------------------------------------------

    /**
     * JS Link Removal
     *
     * Callback function for xss_clean() to sanitize links
     * This limits the PCRE backtracks, making it more performance friendly
     * and prevents PREG_BACKTRACK_LIMIT_ERROR from being triggered in
     * PHP 5.2+ on link-heavy strings
     *
     * @param   array
     * @return  string
     */
    protected function _js_link_removal($match)
    {
        return str_replace(
            $match[1],
            preg_replace(
                '#href=.*?(alert\(|alert&\#40;|javascript\:|livescript\:|mocha\:|charset\=|window\.|document\.|\.cookie|<script|<xss|data\s*:)#si',
                '',
                $this->_filter_attributes(str_replace(array('<', '>'), '', $match[1]))
            ),
            $match[0]
        );
    }

    // --------------------------------------------------------------------

    /**
     * JS Image Removal
     *
     * Callback function for xss_clean() to sanitize image tags
     * This limits the PCRE backtracks, making it more performance friendly
     * and prevents PREG_BACKTRACK_LIMIT_ERROR from being triggered in
     * PHP 5.2+ on image tag heavy strings
     *
     * @param   array
     * @return  string
     */
    protected function _js_img_removal($match)
    {
        return str_replace(
            $match[1],
            preg_replace(
                '#src=.*?(alert\(|alert&\#40;|javascript\:|livescript\:|mocha\:|charset\=|window\.|document\.|\.cookie|<script|<xss|base64\s*,)#si',
                '',
                $this->_filter_attributes(str_replace(array('<', '>'), '', $match[1]))
            ),
            $match[0]
        );
    }

    // --------------------------------------------------------------------

    /**
     * Attribute Conversion
     *
     * Used as a callback for XSS Clean
     *
     * @param   array
     * @return  string
     */
    protected function _convert_attribute($match)
    {
        return str_replace(array('>', '<', '\\'), array('&gt;', '&lt;', '\\\\'), $match[0]);
    }

    // --------------------------------------------------------------------

    /**
     * Filter Attributes
     *
     * Filters tag attributes for consistency and safety
     *
     * @param   string
     * @return  string
     */
    protected function _filter_attributes($str)
    {
        $out = '';

        if (preg_match_all('#\s*[a-z\-]+\s*=\s*(\042|\047)([^\\1]*?)\\1#is', $str, $matches))
        {
            foreach ($matches[0] as $match)
            {
                $out .= preg_replace("#/\*.*?\*/#s", '', $match);
            }
        }

        return $out;
    }

    // --------------------------------------------------------------------

    /**
     * HTML Entity Decode Callback
     *
     * Used as a callback for XSS Clean
     *
     * @param   array
     * @return  string
     */
    protected function _decode_entity($match)
    {
        return $this->entity_decode($match[0]);
    }

    // --------------------------------------------------------------------

    /**
     * Validate URL entities
     *
     * Called by xss_clean()
     *
     * @param   string
     * @return  string
     */
    protected function _validate_entities($str)
    {
        /*
         * Protect GET variables in URLs
         */

        // 901119URL5918AMP18930PROTECT8198

        $str = preg_replace('|\&([a-z\_0-9\-]+)\=([a-z\_0-9\-]+)|i', $this->xss_hash()."\\1=\\2", $str);

        /*
         * Validate standard character entities
         *
         * Add a semicolon if missing.  We do this to enable
         * the conversion of entities to ASCII later.
         *
         */
        $str = preg_replace('#(&\#?[0-9a-z]{2,})([\x00-\x20])*;?#i', "\\1;\\2", $str);

        /*
         * Validate UTF16 two byte encoding (x00)
         *
         * Just as above, adds a semicolon if missing.
         *
         */
        $str = preg_replace('#(&\#x?)([0-9A-F]+);?#i',"\\1\\2;",$str);

        /*
         * Un-Protect GET variables in URLs
         */
        $str = str_replace($this->xss_hash(), '&', $str);

        return $str;
    }

    // ----------------------------------------------------------------------

    /**
     * Do Never Allowed
     *
     * A utility function for xss_clean()
     *
     * @param   string
     * @return  string
     */
    protected function _do_never_allowed($str)
    {
        $str = str_replace(array_keys($this->_never_allowed_str), $this->_never_allowed_str, $str);

        foreach ($this->_never_allowed_regex as $regex)
        {
            $str = preg_replace('#'.$regex.'#is', '[removed]', $str);
        }

        return $str;
    }

    // --------------------------------------------------------------------

    /**
     * Set Cross Site Request Forgery Protection Cookie
     *
     * @return  string
     */
    protected function _csrf_set_hash()
    {
        if ($this->_csrf_hash == '')
        {
            // If the cookie exists we will use it's value.
            // We don't necessarily want to regenerate it with
            // each page load since a page could contain embedded
            // sub-pages causing this feature to fail
            if (isset($_COOKIE[$this->_csrf_cookie_name]) &&
                preg_match('#^[0-9a-f]{32}$#iS', $_COOKIE[$this->_csrf_cookie_name]) === 1)
            {
                return $this->_csrf_hash = $_COOKIE[$this->_csrf_cookie_name];
            }

            return $this->_csrf_hash = md5(uniqid(rand(), TRUE));
        }

        return $this->_csrf_hash;
    }

    /**
     * Remove Invisible Characters
     *
     * This prevents sandwiching null characters
     * between ascii characters, like Java\0script.
     *
     * @access  public
     * @param   string
     * @return  string
     */
    private function remove_invisible_characters($str, $url_encoded = TRUE)
    {
        $non_displayables = array();

        // every control character except newline (dec 10)
        // carriage return (dec 13), and horizontal tab (dec 09)

        if ($url_encoded)
        {
            $non_displayables[] = '/%0[0-8bcef]/';  // url encoded 00-08, 11, 12, 14, 15
            $non_displayables[] = '/%1[0-9a-f]/';   // url encoded 16-31
        }

        $non_displayables[] = '/[\x00-\x08\x0B\x0C\x0E-\x1F\x7F]+/S';   // 00-08, 11, 12, 14-31, 127

        do
        {
            $str = preg_replace($non_displayables, '', $str, -1, $count);
        }
        while ($count);

        return $str;
    }

    /**
     * 格式化请求参数
     * @param  array  $params 请求参数
     * @param  string $from   公钥
     * @param  string $appKey 私钥
     * @return array  $params       格式化后的请求参数
     */
    public function formatParams($params, $from='', $appKey='')
    {
        if(empty($params) || !is_array($params) || empty($from) || empty($appKey))
        {
            return FALSE;
        }

        $nonce  = $this->getRandomStr();
        $time   = time();

        $sign = $this->createB2bApiSign($params, $time, $nonce, $from, $appKey);

        $params['_from']         = $from;
        $params['_nonce']        = $nonce;
        $params['_timestamp']    = $time;
        $params['_sign']         = $sign;

        return $params;
    }

    /**
     * 生成签名
     *
     * @param  $params 解密后的参数
     * @return string 签名字符串
     */
    public function createB2bApiSign($params, $timestamp, $nonce, $from, $appkey)
    {
        if(isset($params['_sign']))
        {
            unset($params['_sign']);
        }

        if(isset($params['_timestamp']))
        {
            unset($params['_timestamp']);
        }

        if(isset($params['_nonce']))
        {
            unset($params['_nonce']);
        }

        if(isset($params['_from']))
        {
            unset($params['_from']);
        }

        ksort($params);

        // $query_string = http_build_query($params);

        $query_string = '';

        foreach($params as $k => $v)
        {
            if(!is_array($v))
            {
                $query_string .= "$k=$v&";
            }
        }

        $query_string = rtrim($query_string, '&');

        //加密
        return mb_strtoupper(md5(md5($query_string) . $nonce . $timestamp . $from . $appkey));
    }

    /**
     * 生成随机字符串
     *
     * @param  int    $length 生成的字符串长度
     * @return string
     */
    public function getRandomStr($length = 8)
    {
        // 密码字符集，可任意添加你需要的字符
        $chars = 'abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789';
        $str   = '';
        for ($i=0; $i<$length; $i++)
        {
            $str .= $chars[ mt_rand(0, strlen($chars) - 1) ];
        }
        return $str;
    }

    /**
     * 验证签名
     * @param  array  $params    请求参数
     * @param  string $appkey   私钥
     * @return bool
     */
    public function checkSignParams($params, $appKey='')
    {
        if(empty($params) || !is_array($params) || empty($appKey) || empty($params['_sign']) || empty($params['_timestamp']) || empty($params['_nonce']) || empty($params['_from']))
        {
            return FALSE;
        }

        $oriSign = $params['_sign'];
        unset($params['_sign']);

        $time = $params['_timestamp'];
        unset($params['_timestamp']);

        $nonce = $params['_nonce'];
        unset($params['_nonce']);

        $from = $params['_from'];
        unset($params['_from']);

        $sign = $this->createB2bApiSign($params, $time, $nonce, $from, $appKey);

        return $sign == $oriSign;
    }

    public function authcode($string, $operation = 'DECODE', $key = '', $expiry = 0) {
        $strConfig = array('+' => '@', '/' => '.');
        // 需要先转换
        if($operation == 'DECODE'){
            foreach($strConfig as $k => $v){
                $string = str_replace($v, $k, $string);
            }
        }
        // 动态密匙长度，相同的明文会生成不同密文就是依靠动态密匙
        $ckey_length = 4;

        // 密匙
        $key = md5($key ? $key : md5('lsf_swoole_framework'));

        // 密匙a会参与加解密
        $keya = md5(substr($key, 0, 16));
        // 密匙b会用来做数据完整性验证
        $keyb = md5(substr($key, 16, 16));
        // 密匙c用于变化生成的密文
        $keyc = $ckey_length ? ($operation == 'DECODE' ? substr($string, 0, $ckey_length):
            substr(md5(microtime()), -$ckey_length)) : '';
        // 参与运算的密匙
        $cryptkey = $keya.md5($keya.$keyc);
        $key_length = strlen($cryptkey);
        // 明文，前10位用来保存时间戳，解密时验证数据有效性，10到26位用来保存$keyb(密匙b)，
        //解密时会通过这个密匙验证数据完整性
        // 如果是解码的话，会从第$ckey_length位开始，因为密文前$ckey_length位保存 动态密匙，以保证解密正确
        $string = $operation == 'DECODE' ? base64_decode(substr($string, $ckey_length)) :
            sprintf('%010d', $expiry ? $expiry + time() : 0).substr(md5($string.$keyb), 0, 16).$string;
        $string_length = strlen($string);
        $result = '';
        $box = range(0, 255);
        $rndkey = array();
        // 产生密匙簿
        for($i = 0; $i <= 255; $i++) {
            $rndkey[$i] = ord($cryptkey[$i % $key_length]);
        }
        // 用固定的算法，打乱密匙簿，增加随机性，好像很复杂，实际上对并不会增加密文的强度
        for($j = $i = 0; $i < 256; $i++) {
            $j = ($j + $box[$i] + $rndkey[$i]) % 256;
            $tmp = $box[$i];
            $box[$i] = $box[$j];
            $box[$j] = $tmp;
        }
        // 核心加解密部分
        for($a = $j = $i = 0; $i < $string_length; $i++) {
            $a = ($a + 1) % 256;
            $j = ($j + $box[$a]) % 256;
            $tmp = $box[$a];
            $box[$a] = $box[$j];
            $box[$j] = $tmp;
            // 从密匙簿得出密匙进行异或，再转成字符
            $result .= chr(ord($string[$i]) ^ ($box[($box[$a] + $box[$j]) % 256]));
        }
        if($operation == 'DECODE') {
            // 验证数据有效性，请看未加密明文的格式
            if((substr($result, 0, 10) == 0 || substr($result, 0, 10) - time() > 0) &&
                substr($result, 10, 16) == substr(md5(substr($result, 26).$keyb), 0, 16)) {
                return substr($result, 26);
            } else {
                return '';
            }
        } else {
            $return = $keyc.str_replace('=', '', base64_encode($result));
            // 定义特殊字符转义
            foreach($strConfig as $k => $v){
                $return = str_replace($k, $v, $return);
            }
            // 把动态密匙保存在密文里，这也是为什么同样的明文，生产不同密文后能解密的原因
            // 因为加密后的密文可能是一些特殊字符，复制过程可能会丢失，所以用base64编码
            return $return;
        }
    }
}
